This invention relates to conveyor ovens. More particularly, this invention relates to a method of cooking foods in a conveyor oven using infrared energy from both electric heaters and from gas-fired infrared heaters. In other words, this invention relates to a method of controlling a hybrid oven.
Heat transfer occurs in at least one of three ways: conduction; convection and radiation. Conduction requires direct physical contact between two objects, such as the direct physical contact that occurs between a frying pan and a food being fried. Convection relies on heat transfer via a liquid or gas. In a conventional oven, heated air molecules bump into other molecules and transfer some of their energy into a food being baked. Infrared heat, is different. It heats by transferring electromagnetic energy. It does not rely on any intermediary to conduct heat because it works directly on molecules in its path.
FIG. 1 depicts the relationship between IR radiation emitted from a surface as a function of wavelength at various surface temperatures. Surfaces temperatures above about 2000 degrees C. will emit relatively short wavelength IR that is in the visible spectrum. Short wavelength IR is known to penetrate materials more deeply than long wavelength IR. At surface temperatures below 900 degrees C., the emitted IR is of a much longer wavelength, less “intense” and less penetrating.
Since all heat transfer involves some loss or inefficiency, radiant cooking is more energy efficient because less energy is lost heating a conductor, whether the heat conductor is a solid material, such as a frying pan, or the air enclosed in a conventional oven. Cooking with infrared heat is therefore faster and more energy efficient than either conduction or convention.